1. Technical Field
The disclosure relates to light emitting apparatuses, and particularly to a light emitting diode (LED) element with a symmetric luminous distribution and a direct-type backlight module using the same, wherein the LED element has an elongated (rectangular) LED and a lens for converting light from the LED which is originally asymmetric in X-axis and Y-axis distribution into the symmetric luminous distribution in both the X-axis and Y-axis.
2. Description of Related Art
A conventional direct-type backlight module served as a backlight source for an LCD (liquid crystal display) television or an LCD monitor includes a number of LEDs, and a diffusing plate located above the LEDs. A larger distance should be kept between each of the LEDs and the diffusing plate, so that light generated from the LEDs is not concentrated in some points of the diffusing plate of the direct-type backlight module. If the distance between each of the LEDs and the diffusing plate is increased, a thickness of the direct-type backlight module would be increased accordingly, which is unfavorable for the compact tendency of electronic device. Therefore, a number of lenses are provided to cover the LEDs, so that the number of the LEDs needed and the thickness of the direct type backlight module are reduced, and the light inputting angle of light entering the diffusing plate is converted (diffused) by the lenses before the light emitted from the LEDs enters the diffusing plate. The LEDs used in the direct type backlight module are square LEDs with symmetric luminous distribution. LEDs used in the edge-type backlight module are elongated LEDs with asymmetric luminous distribution. However, the elongated LEDs can only be used in the edge-type backlight module and can not be used in the direct-type backlight module, which results in increased costs for inventory management of the LEDs.
What is needed, therefore, is an LED element having an elongated LED and a direct-type backlight module using the same which can overcome the limitations described above.